package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.redisson.api.GeoUnit;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service

public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;
    @Override
    public Result queryById(Long id) {
        //缓存击穿
//        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        //互斥锁解决击穿
//        Shop shop = queryWithMutex(id);
        //逻辑过期解决击穿
        Shop shop = cacheClient.queryWithLogicalExpire
                (CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        if (shop == null){
            return Result.fail("店铺不存在");
        }
        //返回
        return Result.ok(shop);
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

public Shop queryLogicalExpire(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从Redis中查询店铺数据
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断缓存是否命中
        if (StrUtil.isBlank(shopJson)) {
            // 3. 缓存未命中，返回错误
            return null;
        }
        //4.命中需要先把JSON反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1未过期，直接返回店铺信息
            return shop;
        }
        //5.2 已过期,需要缓存重建
        //6.缓存重建
        //6.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        //6.2判断是否获取锁成功
        boolean isLock = tryLock(lockKey);
        if (isLock) {
            //6.3成功,开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    //重建
                    this.saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unLock(lockKey);
                }
            });
        }
        //6.4返回失败信息

        //数据库中存在，写入Redis，并返回店铺数据
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }
    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    public Shop queryWithMutex(Long id)  {
        String key = CACHE_SHOP_KEY + id;
        //从Redis中查询店铺数据
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        Shop shop = null;
        //判断缓存是否命中
        if (StrUtil.isNotBlank(shopJson)) {
            // 2.1 缓存命中，直接返回店铺数据
            shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断命中是否为空值
        if (shopJson != null){
            //返回错误信息
            return null;
        }
        //实现缓存重建
        try {
            //获取互斥锁
            boolean islock = tryLock(LOCK_SHOP_KEY + id);
            //判断是否获取成功
            if(!islock){
                //如果失败，则休眠重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //成功，根据id查询数据库
            shop = this.getById(id);
            //模拟重建时延迟
            Thread.sleep(200);
            //判断数据库是否存在店铺数据
            if (Objects.isNull(shop)) {
                //将空值写入Redis
                stringRedisTemplate.opsForValue().set(key, "",CACHE_NULL_TTL, TimeUnit.MINUTES);
                //数据库中不存在，返回失败信息
                return null;
            }
            //数据库中存在，写入Redis，并返回店铺数据
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            e.printStackTrace();

        }finally {
            //释放互斥锁
            unLock(LOCK_SHOP_KEY + id);
        }
        //返回
        return shop;
    }
    public Shop queryWithPassThrough(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //从Redis中查询店铺数据
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        Shop shop = null;
        //判断缓存是否命中
        if (StrUtil.isNotBlank(shopJson)) {
            // 2.1 缓存命中，直接返回店铺数据
            shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断命中是否为空值
        if (shopJson != null){
            //返回错误信息
            return null;
        }
        //缓存未命中，从数据库中查询店铺数据
        shop = this.getById(id);

        //判断数据库是否存在店铺数据
        if (Objects.isNull(shop)) {
            //将空值写入Redis
            stringRedisTemplate.opsForValue().set(key, "",CACHE_NULL_TTL, TimeUnit.MINUTES);
            //数据库中不存在，返回失败信息
            return null;
        }
        //数据库中存在，写入Redis，并返回店铺数据
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }

    public   void  saveShop2Redis(Long id ,Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null){
            return Result.fail("店铺id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //判断是否需要坐标查询
        if (x == null || y == null){
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            return Result.ok(page.getRecords());
        }
        //计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        //查询redis，按照距离排序。结果：shopId，distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoRadiusCommandArgs.newGeoRadiusArgs().includeDistance().includeCoordinates().limit(end)
        );
        //解析出id
        if (results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from){
            return Result.ok(Collections.emptyList());
        }
        //截取from到end
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(
                result -> {
                    //获取店铺id
                    String shopIdStr = result.getContent().getName();
                    ids.add(Long.valueOf(shopIdStr));
                    //获取距离
                    Distance distance = result.getDistance();
                    distanceMap.put(shopIdStr, distance);
                }
        );
        //根据id查询shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("order by field (id,+" + idStr + ")").list();
        //返回
        for (Shop shop : shops) {
            Distance distance = distanceMap.get(shop.getId().toString());
            shop.setDistance(distance.getValue());
        }
        return Result.ok(shops);
    }

}
